This invention relates to improved silica containing non-skid compositions applied to the surfaces of paper products such as corrugated board, paperboard, linerboard and the like, whether virgin or recycled.
In paper mills, such as a plant producing corrugated board for example, it has long been the practice to apply non-skid compositions to at least selected surface areas of the paper product to decrease the slipperiness of the product and facilitate handling, stacking and the like. The non-skid composition of choice has been an aqueous dispersion of colloidal silica, preferably amorphous silica, which may optionally include urea. Additionally, the dispersion may include small amounts (less than 1 part in a 100) of rust inhibitors such as sodium nitrite and/or sodium benzoate, preservatives, alkaline agents to stabilize the silica dispersion, defoamers and the like as is known in this art. All such compositions are referred to hereinafter collectively as "aqueous dispersions of colloidal silica".
The application of the non-skid composition to the paper product is most commonly accomplished by means of low pressure spray heads. Such application has been a source of problems since these dispersion compositions exhibit a great tendency to mist excessively throughout the spray area, distributing the composition over personnel and equipment with drifting fog and clouds and also tending to clog the spray heads. Since spray application is deemed preferred, these non-skid compositions consisting essentially of aqueous dispersions of colloidal silica need to be modified in such a way as to limit and control the misting thereof. This is a primary objective of this invention which provides improved non-skid compositions, substrates carrying those compositions and methods of improving such compositions.